This invention relates to drilling apparatus of the type which embodies an elongated frame which supports a transmission unit for longitudinal movement thereof with the transmission unit operatively connecting a polygonal drive shaft to a driven head which is threadedly connected to a drill rod section for drilling a hole into the earth.
Heretofore in the art to which my invention relates, it has been the usual practice to position the drill rod sections sequentially in axial alignment with the driven head of the apparatus by employing a rotatable drill rod rack which was supported outwardly of the frame carrying the drilling apparatus. Such prior art drill rod racks have been supported by arms which swing the entire drill rod rack from the outer inoperative position to an inner operative position. Accordingly, such drill rod racks not only require rotation of the drill rod rack to position selected ones of the drill rod sections in position to move beneath the driven head but also the entire drill rod rack must be swung from the position outwardly of the drill rod frame to a position to align a drill rod section with the driven head. This requires a considerable amount of time and effort due to the fact that the drilling operation must be stopped as the entire drill rod rack is swung from the outer inoperative position to the inner position in addition to the time required to rotate the drill rod rack to position the next drill rod section in proper position to move into axial alignment with the driven head.
Difficulties have also been encountered in providing quick-acting breaker units for breaking the joint between the drill rod section and another drill rod section or a drill bit. That is, such breaker units are complicated in structure and require manual actuation of the various components of the breaker units. This not only requires a considerable amount of time and effort on the part of the worker but also requires that the worker be present at the location of the joint being broken or made, thus exposing the worker to the elements and also to the danger encountered in handling drill rod sections as the joints are made or broken.